Airborne police have found and destroyed $2 million worth of cannabis as the marijuana growing season closes.

Police assisted by the air force found more than 2000 marijuana plants growing outdoors across the Auckland region in the past two weeks, with officers winched down from a helicopter to the plots.

"The plants were growing in forests, swamps, rivers and rural property, and crops were found in a number of different locations, including Port Waikato, Muriwai, Piha, Kaipara Flats, Helensville and Great Barrier Island," police said.

Head of the operation Detective Sergeant Callum McNeill said 16 search warrants had been executed and so far seven men and one woman had been charged with cultivating cannabis.

"This is a great result," McNeill said.

"Some of the plants that we seized had obviously been growing for quite some time and I have no doubt that this has dealt a real blow to the criminal element.

"Every year, around the time that criminals plant cannabis, we ask the public to tell us about any suspicious behaviour they may see. Part of this week's result owes its success to the information provided by the community."